1. Field of the Invention
The present invention relates to a flat cable manufacturing device, in which a plurality of wire conductors are arranged in parallel at a given interval from each other, and are enclosed by a pair of insulator films.
2. Description of Background Information
Such a flat cable exists in the prior art and is known to have the advantages of requiring less space and reducing the total weight per conductor capacity, compared to individual wires. The above insulator films is formed of e.g. a polyester-based material, in which a good insulator material, e.g. polyethylene terephthalate (PET), is used as a base portion, one of its faces being coated with an adhesion layer made of a thermoplastic material, for instance.
FIG. 1 shows an example of known methods for manufacturing such flat cables. The base portion of the insulator films 1 and 2 is made of PET or the like. The adhesion layer is heat-fusible material having a thickness of e.g. 40 xcexcm provided on one surface of the base portion. The insulator films 1 and 2 are superposed on a plurality of regularly arranged wire conductors 3 with the adhesion layers facing each other. The films are then passed between hot pressure rolls 4, 5 for hot-press adhesion. The adhesion layers are thereby melted, causing the insulator films 1, 2 to be adhered to each other.
Note that for the insulator films to be adhered properly, the above method requires that the adhesion layers be melted down by conducting heat right through their thickness. For a good adhesion, the adhesion layers must be melted down thoroughly. This often leads to a relatively long transformation time and a low productivity.
Furthermore, when the adhesion layers are not sufficiently thick, the insulator films 1 and 2 cannot be adequately adhered to the wire conductors 3. However, if the adhesion layers are thick, the insulator films 1 and 2 cannot be separated easily from the wire conductors 3. This creates problems when recycling disused cables. In addition, the material forming the adhesion layer may be contaminated with the insulator films 1 and 2, tending to make recycling inefficient.
To avoid such problems, there had been proposed insulator films having no adhesion layer coating. Alternatively, as is disclosed in JP-A-Hei-9-259 662, the base portion material and adhesion layer (1 to 3 xcexcm thick) of the insulator film can be formed of the same type of material, and adhered by ultrasonic welding.
One such method is shown in FIG. 2. According to this method, two insulator films 11 and 12 are prepared, each having a thin adhesion layer on one surface. They are respectively stored coiled respectively around a top film roll 13 and a bottom film roll 14, such that upon being uncoiled in the manufacturing process, the adhesion layers are mutually superposed. Upon being unrolled from the above-mentioned top and bottom film rolls 13 and 14, the insulator films 11, 12 are supplied to a pair of hot rolls 15 and 16 for press adhesion at 170xc2x0 C. At the same time, a plurality of wire conductors 20 are uncoiled from corresponding conductor supply rolls 17 and forwarded to a pair of pitch guides 18 and 19, causing the wire conductors 20 to be arranged in parallel at a given pitch relative to each other. The wire conductors 20 and the pair of insulator films 11 and 12 are then supplied synchronously to the hot rolls 15 and 16, such that the wire conductors 20 are interposed between the adhesion layers of the insulator films 11 and 12.
There is further provided an ultrasonic welding machine 21 comprising a horn 22 and an anvil 23. At least one of the horn 22 and anvil 23 includes a plurality of surface grooves corresponding to the passages for the wire conductors 20, such that the surface of at least one of the horn or anvil forms an alternating protrusion-and-recess profiled cross-section. The horn 22 and the anvil 23 hold the insulator films 11 and 12 by the interval areas, or spaces, between the passages for the wire conductors 20. The horn 22 is then supplied to ultrasonic energy, so that those interval areas of the insulator films 11, 12 held by the horn 22 and anvil 23 are heat-melted. The melted portions are cooled and solidified by a cooling unit, e.g. cold-air jetting.
Thereafter, the two longitudinal rim portions of the insulator films 11 and 12 are trimmed by a pair of side cutters 24. The heat-welded insulator films 11 and 12 are then forwarded further by intermittent drive motion generated by a pair of stepping rollers 26 and 27 which is linked to a stepping motor. The insulator films 11 and 12 are passed through a guide roller 28 and coiled around a coiling roll 29.
According to such a flat cable manufacturing method, the longitudinal rim portions (longitudinal edges) of the welded insulator films 11 and 12 must be suitably regulated such as to yield a constant width. The ultrasonic welding machine 21 and the side-cutter 24 must also be appropriately distanced, so that the hot welded insulator films 11 and 12 are sufficiently cooled down before they are cut off by the side-cutters 24.
However, the above-mentioned distance between the welding machine and the cutter tends to allow the insulator films 11 and 12 to deviate in the width direction during the forwarding, so that the cutting margins in the width direction fluctuate constantly.
Further, when both of the longitudinal rim portions are not sufficiently cooled down while cutting-off, the insulator films 11 and 12 tend to droop. In such a case, a high-speed flat cable production is rendered virtually impossible.
The present invention therefore aims to provide a flat-cable manufacturing device, which is capable of cutting the longitudinal rim portions (longitudinal edges) of the insulator films with high precision and at a high speed.
To this end, there is provided an ultrasonic welding and cutting device for use in the manufacture of a flat-cable, the flat cable including a plurality of wire conductors which are arranged in parallel at a given interval to each other and interposed between first and second insulator films, the device having a product flow line in an upstream to downstream direction, and including a horn unit that imparts ultrasonic oscillations, the horn unit including a horn melter unit, and a horn cutter unit, the horn melter unit and the horn cutter unit being located sequentially from upstream to downstream at a predetermined distance along the product flow line; and an anvil unit including an anvil melter unit and one or several anvil blade unit(s), the anvil melter unit and the anvil blade unit(s) respectively facing the horn melter unit and the cutter unit along the product flow line;
such that, when the first and second insulator films containing the plurality of wire conductors are passed between the horn and anvil unit, the first and second insulator films can be fused and adhered by the horn and anvil melter units, and successively fused and cut or trimmed by the horn cutter unit and anvil blade unit(s), respectively along the product flow line.
Preferably, the anvil melter unit and horn melter unit have respective surfaces facing each other, and at least one of the surfaces includes a plurality of conductor-path grooves formed correspondingly to the plurality of wire conductors, such that, when the horn melter unit is moved toward to the anvil melter unit, the wire conductors are placed in the conductor-path grooves, and such that, while an upstream portion of the first and second insulator films is ultrasonically fused and welded, the horn cutter unit and the anvil blade unit are placed into contact and a downstream portion of ultrasonically welded first and second insulator films is ultrasonically cut off.
The anvil melter unit may have a cylindrical form with a circular surface, and the conductor-path grooves may be formed on the circular surface.
Preferably, the device further includes an anvil cylinder unit having grooves, which has the same configuration as that of the anvil melter unit and is placed downstream the anvil blade unit(s) along the product flow line.
Preferably yet, each of the anvil blade unit(s) has a configuration such that it can be freely fitted into, or removed from, the space formed between a conductor-path groove of the anvil melter unit and the corresponding groove of the anvil cylinder unit, and held therebetween.
Typically, the horn melter unit has an arc-shaped form projecting towards the anvil melter unit.
Further, the horn cutter unit may have a surface facing the anvil blade unit, and the surface may be provided with ceramic chips.
Suitably, the device further includes a regulating mechanism that regulates a contact pressure of the anvil blade unit against the horn cutter unit.
The invention further relates to a system for manufacturing a flat cable, the system having a product flow line in an upstream to downstream direction, and including mechanism for arranging a plurality of wire conductors in parallel at a given interval to each other; mechanism for interposing the wire conductors between first and second insulator films; such that the first and second insulator films face each other at the given interval between the wire conductors; and an ultrasonic welding and cutting unit including a horn unit for imparting ultrasonic oscillations comprising a horn melter unit and a horn cutter unit, the horn melter unit and the horn cutter unit being located sequentially from upstream to downstream at a predetermined distance along the product flow line; and an anvil unit including an anvil melter unit and one or several anvil blade unit(s), the anvil melter unit and the anvil blade unit(s) respectively facing the horn melter unit and the horn cutter unit along the product flow line; such that, when the first and second insulator films containing the plurality of wire conductors are passed between the horn and anvil units, the first and second insulator films can be fused and adhered by the horn and anvil melter units, and successively fused and cut or trimmed by the horn cutter unit and anvil blade unit, respectively along the product flow line.
Preferably, the system further includes mechanism for providing adhesion layers to the first and second insulator films upstream of the ultrasonic welding and cutting mechanism, the adhesion layers being supplied on the surface of each of the first and second insulator films which faces the wire conductors.
The invention also concerns a method for manufacturing a flat cable having a product flow line in an upstream to downstream direction, and includes arranging a plurality of wire conductors in parallel at a given interval to each other; interposing the wire conductors between first and second insulator films; whereby the first and second insulator films face each other at the given interval between the wire conductors; and ultrasonically welding and cutting by using: a horn unit that imparts ultrasonic oscillations, the horn unit including a horn melter unit and a horn cutter unit, the horn melter unit and the horn cutter unit being located sequentially from upstream to downstream at a predetermined distance along the product flow line; and an anvil unit comprising an anvil melter unit and one or several anvil blade unit(s), the anvil melter unit and the anvil blade unit(s) respectively facing the horn melter unit and the horn cutter unit along the product flow line; whereby, when the first and second insulator films containing the plurality of wire conductors are passed between the horn and anvil units, the first and second insulator films can be fused and adhered by the horn and anvil melter units, and successively fused and cut or trimmed by the horn cutter unit and the anvil blade unit, respectively along the product flow line.